Genetic diversity, phylogenetic structure and development of core collections in Melilotus accessions from a Chinese gene bank

Abstract

Abstract Melilotus is an important forage legume, with high values as feed and medicine, and widely used as green manure, honey plant, and wildlife habitat enhancer. The genetic diversity, structure and subdivision of this forage crop remain unclear, and plant genetic resources are the basis of biodiversity and ecosystem diversity and have attracted increasing attention. In this study, the whole collection of 573 accessions from the National Gene Bank of Forage Germplasm (NGBFG, China) and 48 accessions from the National Plant Germplasm System (NPGS, USA) in genus Melilotus were measured with respect to five seed characters: seed length, width, width-to-length ratio, circumference and 100-seed weight. Shannon’ genetic diversity index (H’) and phenotypic differentiation (Pst) were calculated to better describe the genetic diversity. The ITS and matK sequences were used to construct phylogenetic trees and study the genetic relationships within genus Melilotu. Based on seed morphology and molecular marker data, we preliminarily developed core collections and the sampling rates of M. albus and M. officinalis were determined to be 15% and 25%, respectively. The results obtained here provide preliminary sorting and supplemental information for the Melilotus collections in NGBFG, China, and establish a reference for further genetic breeding and other related projects.